The letter H as used in the design itself has 12,621 nodes in it and in the above screen shot is used twice. The lowercase f has 6,004 points. The lowercase v has 3,500 nodes. And so on. Just those three letters have one heck of a lot of nodes.

fwiw, I PDF'd a full specimen sheet from ID and it went through a Xerox and my ancient HP 4MV just fine using Acrobat Pro 9.

In Acrobat 10, we removed the stupid Convert TrueType to Type 1 option simply because it made no sense. If you have a PostScript device that supports Type 42 fonts (i.e., TrueType fonts in a PostScript environment), there is no go reason to convert same to unhinted Type 1 fonts. The printer simply doesn't need such a conversion and whenever a conversion of this nature is required, there is always the chance of something going wrong ... which was apparently the case here.

Quite frankly, there hasn't been a new PostScript printer sold in the last fourteen years or more that doesn't handle TrueType fonts natively. That's why we removed the option for Acrobat 10. If you are printing to an ancient PostScript Level 2 printer that doesn't support TrueType (although most PostScript Level 2 printers do support native TrueType including all the LaserJet 4M, 5M, and 6M products), we silently continue to do that conversion of TrueType fonts. In this particular case, if you had such an ancient printer and this particular font (which by the way seems ridiculously complex if a single glyph has thousands of nodes in its definition), you would still see a failure.

I went ahead and bought the font just to see how complex it was. Exporting the letters I mentioned above as EPS files and taking them into Illustrator, they could have been simplified easily. The node count was from Illy's Path Simplify window. Depending on the character there was between a 50% to 65% node reduction before any particular glyph began to loose noticeable detail.

The font author could have had a much cleaner, albeit still complex, font with little extra effort during his digitizing of the design.

"OpenType" is a wrapper name for two different sets of font outlines -- two that have been competing for years, now finally unified into a single type. Well, sort of, anyway ... (Imagine a single file format that "unifies" Illustrator and InDesign documents -- and the very first byte inside that file tells you if it "is" an InDesign document or Illustrator drawing. It's something like that. But user software should not be able to tell whether it got one type of font outlines or another, so from that point of view there "is" no difference.)

Between TrueType and Type 1 OpenType files there are lots of minor differences (internally, TrueType requires more data tables than Type 1 -- but, again, nothing you'd usually notice as a user), and one pretty major difference.

In a Type 1 font (a.k.a. "CFF", for "Compact Font Format") all characters are internally described by a simplified version of PostScript. In ye olden days, it meant that for every single character that got drawn, your trusty old PostScript printer simply reset a few values -- scale, transformations -- and "ran" the tiny PostScript program describing that single character. When it was done, the PS printer restored what values it changed and continued with the rest of the PostScript commands it encountered.

A TrueType font, on the other hand, does not really define "line here, curve there", but is more like a very small computer program which return a set of lines to be filled as "output". The major advantage over PS fonts was that this little program could be instructed to "round" values towards actual pixel coordinates, meaning that on a very small size, each of the defined points for lines and curves could 'snap' to the nearest pixel. That meant those fonts could be optimized for screen usage; on the other hand, when printing, this rounding is so infinitesimally small that it's virtually unnoticeable on a 600 dpi printer.

A similar "screen hinting" mechanism is also part of the CFF specifications, by the way, so for a well designed and hinted font you ought not to see any visual difference on screen.

There is a technical aspect involved as well; PostScript fonts use 3nd order Bezier curves (cubic), TrueType fonts use 2nd order Bezier curves (quadratics). Cubic Beziers can be converted to quadratics without any loss of precision, but not the other way around. Much like you can draw a rectangle out of triangles, but not the reverse

Usually there is no visible loss of quality after such a conversion (unless someone killed or mangled the different types of hinting, of course).

As Dov says, for any modern 21st century system, conversion should never be necessary. In the past, TrueType fonts had a bad reputation -- but current viewpoint on that is that was just because there were lots of sub-quality amateur TrueType fonts; most serious font foundries created their fonts as Type 1. It's a fair guess that was because the professional output devices of that time were in fact powered by PostScript. Which was, incidentally, the very foundation of Adobe's success.